At your Bash prompt, press Ctrl–v Ctrl–Left-Arrow and Ctrl–v Ctrl–Right-Arrow and make note of the output. You should see something like: ^[OD and ^[OC or similar. Add the following lines to your ~/.inputrc:
"\eOC": forward-word
"\eOD": backward-word
where you will substitute \e for escape (^[) and the rest of the characters you got (OD, OC or similar).
To re-read the file and make the changes active immediately, press Ctrl–x Ctrl–r.